/*
 * ***** BEGIN LICENSE BLOCK *****
 * Version: MPL 1.1
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is
 *
 * java-concurrency-presentation:
 * concurrency presentation tutorial.
 *
 * The Initial Developer of the Original Code is
 * Marco Antonio Villalobos, Jr.
 * Portions created by the Initial Developer are Copyright (C) 2010
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s): None.
 *
 * ***** END LICENSE BLOCK *****
 */

package presentation.concurrency.slides;

import java.util.concurrent.atomic.AtomicInteger;

/**
 * Provides an example on how to use thread local.
 *
 * This example will create a unique id for each thread that calls it.
 */
public class UniqueThreadIdGenerator {

    /** The cached unique id values that are incremented. */
    private static final AtomicInteger uniqueId = new AtomicInteger(0);

    /** A thread local reference to a unique number. */
    private static final ThreadLocal<Integer> uniqueNum =
            new ThreadLocal<Integer>() {
                @Override
                protected Integer initialValue() {
                    return uniqueId.getAndIncrement();
                }
            };

    /**
     * Retrieves the unique number that was generated for this thread.
     *
     * @return The thread id.
     */
    public static int getCurrentThreadId() {
        return uniqueId.get();
    }
}